中文摘要：

利用扫描电镜（SEM）并配合能谱（EDS）分析研究了超高压凝固Mg-6Zn-3Y合金的晶体形态和相演变.实验结果表明：随着凝固压力的增大,α-Mg晶体的形态发生了粗大树枝晶→超细树枝晶→胞状晶转变,即晶体的生长方式逐渐由树枝晶生长→胞状生长过渡.GPa级超高压下凝固极大地提高了Zn在基体中的溶解度,使之成为过饱和固溶体,并随着凝固压力的增大促使Zn的分布趋于均匀化.Mg-6Zn-3Y合金在2 GPa超高压凝固条件下形成了新相Y固溶体,室温组织由4相组成;在6 GPa超高压凝固条件下大量粒状相均匀弥散地分布在基体上,Mg-6Zn-3Y合金的硬度显著提高.

英文摘要：

The solidification microstructure of Mg-6Zn 3Y alloy under super-high pressure was investigated by SEM and EDS.The results show that solidification microstructure of Mg-6Zn-3Y alloy under super high pressure（GPa level） could be evidently refined and was further refined with the increase of solidification pressure.Solubility of Zn in the alloy reached up to 1.64%under 4 GPa pressure which was increased by 44%than that under the atmosphere condition.Y is insoluble in the matrix,which resulted in a new phase riched in Y and granular phases which were dispersed in the matrix.The morphology of crystal changes follow：bulky branch crystal→superfine branch crystal→cellular crystal,and the growth of crystal changed from branch growth to cellular growth.